Glass windows are the conventional means for illuminating rooms with daylight. However, ordinary windows have some disadvantages in respect to natural illumination of rooms. One disadvantage is that daylight does not penetrate very deeply into rooms from ordinary windows. The illumination provided through ordinary windows tends to fall almost exponentially with distance from the window. A second disadvantage of ordinary windows is that direct sunlight entering through the windows will produce areas of very intense illumination in areas close to the window that give rise to thermal discomfort and reflected glare.
Thus, an objective of this invention is a method for producing a thin panel, suited for installation in a window, that channels or redirects all, or a very high proportion of, the sunlight incident from the sky onto the panel, into an upwards direction and over the ceiling of the room being illuminated by the window. This channelling or redirection of all incident sunlight into an upwards direction providing for nearly complete shading from incident sunlight of areas of the room in the vicinity of the window which would otherwise receive intense direct sunlight and providing for natural illumination of areas deep inside the room by diffuse reflection of redirected light off the ceiling.